A metallic microlattice is a synthetic porous metallic material consisting of an ultra-light metal foam. With a density as low as 0.9 mg/cm3(0.00561 lb/ft3), it is one of the lightest structural materials known to science. It was developed by a team of scientists from California-based HRL Laboratories, in collaboration with researchers at University of California, Irvine and Caltech, and was first announced in November 2011. The prototype samples were made from a nickel-phosphorus alloy. In 2012, the microlattice prototype was declared one of 10 World-Changing Innovations by Popular Mechanics. Metallic microlattice technology has numerous potential applications in automotive and aeronautical engineering. A detailed comparative review study among other types of metallic lattice structures showed them to be beneficial for light-weighting purposes but expensive to manufacture.
A metallic microlattice is composed of a network of interconnecting hollow struts. In the least-dense microlattice sample reported, each strut is about 100 micrometres in diameter, with a wall 100 nanometres thick. The completed structure is about 99.99% air by volume, and by convention, the mass of air is excluded when the microlattice density is calculated. Allowing for the mass of the interstitial air, the true density of the structure is approximately 2.1 mg/cm3 (2.1 kg/m3), which is only about 1.76 times the density of air itself at 25 °C. The material is described as being 100 times lighter than Styrofoam.
Metallic microlattices are characterized by very low densities, with the 2011 record of 0.9 mg/cm3 being among the lowest values of any known solid. The previous record of 1.0 mg/cm3 was held by silica aerogels, and aerographite is claimed to have a density of 0.2 mg/cm3. Mechanically, these microlattices are behaviorally similar to elastomers and almost completely recover their shape after significant compression. This gives them a significant advantage over earlier aerogels, which are brittle, glass-like substances. This elastomeric property in metallic microlattices furthermore results in efficient shock absorption. Their Young's modulus E exhibits different scaling, with the density ρ, E ~ ρ2, compared to E ~ ρ3 in aerogels and carbon nanotube foams.
Written By Bhai loog
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